Bluetooth - Ultra Wideband Synchronization

ABSTRACT

Methods, systems, and apparatuses are presented to utilize Bluetooth (BT) radios to synchronize ultra wideband (UWB) radios, to allow the UWB radios to operate within narrow transmit/receive windows, which may lead to power savings. In some implementations, a transmitting UWB radio and a receiving UWB radio may synchronize the expected time of an UWB transmission based on BT events, such as receiving a BT advertisement, or establishing a BT connection. In some implementations, the transmitting UWB radio and the receiving UWB radio may synchronize the expected time of an UWB transmission based on synchronized event counters maintained by the BT radios. Information regarding UWB transmission start times may also be passed via BT communications, in some implementations.

PRIORITY CLAIM

This application claims benefit of priority of U.S. provisionalapplication Ser. No. 62/897,100, titled “Bluetooth—Ultra WidebandSynchronization”, filed Sep. 6, 2019, which is hereby incorporated byreference in its entirety as though fully and completely set forthherein.

TECHNICAL FIELD

The present application relates to wireless communication, including totechniques for synchronizing high-power radios via communications bylower-power radios.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. Further,wireless communication technology has evolved from voice-onlycommunications to also include the transmission of data, such asInternet and multimedia content.

Mobile electronic devices may take the form of smart phones or tabletsthat a user typically carries. Wearable devices (also referred to asaccessory devices) are a newer form of mobile electronic device, oneexample being smart watches. Additionally, low-cost low-complexitywireless devices intended for stationary or nomadic deployment are alsoproliferating as part of the developing “Internet of Things”. In otherwords, there is an increasingly wide range of desired devicecomplexities, capabilities, traffic patterns, and other characteristics.

Such varied wireless communication devices may utilize a number ofdifferent radio access technologies (RATs) and/or radios. For example,various RATs may have advantages and disadvantages relative to otherRATs. For example, a first RAT, such as Bluetooth, may operate withrelatively little power consumption. A second RAT, such as ultrawideband (UWB) may be more capable of performing multipath isolation orranging operations, but may consume power at a higher rate whileoperating in a fully operational state. In particular, certainhigh-power radios, such as UWB may consume large amounts of power duringinitial synchronization, as they may traditionally be required to remainin a fully operational state for a prolonged period of time whilelistening for neighboring devices.

Accordingly, improvements in the field are desired.

SUMMARY

Embodiments are presented herein of, inter alia, systems, apparatuses,and methods for utilizing Bluetooth (BT) radios to synchronize ultrawideband (UWB) radios, to allow the UWB radios to operate within narrowtransmit/receive windows.

A wireless communication device is disclosed, which may include a firstradio, a second radio, and a processor. The first radio may beconfigured to establish a connection with a remote wireless deviceaccording to a first radio access technology (RAT) and provide anindication to the processor that the connection has been established.After providing the indication, the first radio may receive, from theremote wireless device, a notification that the remote wireless devicewill transmit a communication according to a second RAT, wherein thenotification includes an offset time. The first radio may be furtherconfigured to provide the offset time to the processor. The processormay be configured to store a timestamp indicating a time at which theprocessor receives the indication that the connection has beenestablished; and provide to the second radio an instruction to receivethe communication according to the second RAT at a set time, wherein theset time is determined by adding the offset time to the time indicatedby the timestamp. The second radio may be configured to, in response toreceiving the instruction to receive the communication according to thesecond RAT, transition from a low-power state to a high-power state atthe set time and receive the communication according to the second RAT.The second radio may be configured to transition from the high-powerstate to the low-power state after receiving the communication accordingto the second RAT.

In some scenarios, the first RAT may be Bluetooth and the second RAT maybe ultra wideband (UWB).

In some scenarios, in establishing the connection with the remotewireless device according to the first RAT, the first radio may beconfigured to receive, from the remote wireless device, an advertisementmessage according to the first RAT; and transmit, to the remote wirelessdevice, a connection request message according to the first RAT, inresponse to receiving the advertisement message. In some scenarios, inproviding the indication to the processor that the connection has beenestablished, the first radio may be configured to provide an indicationto the processor that the connection request has been transmitted.

In some scenarios, in providing to the second radio the instruction toreceive the communication according to the second RAT at a set time, theprocessor may be configured to initiate a timer configured to expire atthe set time. In response to expiration of the timer, the processor mayprovide to the second radio an instruction to immediately receive thecommunication according to the second RAT.

In some scenarios, in transitioning from a low-power state to ahigh-power state at the set time, the second radio may be configured toreceive from the processor an indication of the time remaining until theset time. In response to expiration of the time remaining, the secondradio may transition from the low-power state to the high-power state.

In some scenarios, the communication according to the second RAT may bean ultra wideband (UWB) ranging request message. In such scenarios, thesecond radio may be further configured to transition from the low-powerstate to the high-power state at a predetermined time after receivingthe UWB ranging request message; in response to receiving the UWBranging request message, transmit an UWB ranging response message whileoperating in the high-power state; and transition from the high-powerstate to the low-power state after transmitting the UWB ranging responsemessage.

A wireless communication device is disclosed, which may include a firstradio and a second radio. The first radio may be configured to maintainan event counter that is incremented in response to a periodic handshakeprocedure with a remote wireless device, according to a first radioaccess technology (RAT). The first radio may further be configured toreceive, from the remote wireless device, a notification that the remotewireless device will transmit a communication according to a second RAT,wherein the notification indicates a future value of the event counterat which the communication will be transmitted. The second radio may beconfigured to transition from a low-power state to a high-power statewhen the event counter reaches the future value indicated in thenotification that the remote wireless device will transmit thecommunication according to the second RAT. The second radio may furtherbe configured to receive the communication according to the second RAT,and transition from the high-power state to the low-power state afterreceiving the communication according to the second RAT.

In some scenarios, the first radio may be further configured toestablish a connection with the remote wireless device according to thefirst RAT prior to receiving the notification that the remote wirelessdevice will transmit the communication according to the second RAT.

In some scenarios, the wireless communication device may further includea processor. The first radio may be further configured to provide to theprocessor the future value of the event counter, as well as a value ofthe event counter that is current at the time the first radio providesto the processor the future value of the event counter. The processormay be configured to, in response to determining that the event counterhas reached the future value, provide to the second radio an instructionto receive the communication according to the second RAT. The secondradio transitioning from the low-power state to the high-power state maybe in response to receiving the instruction from the processor.

In some scenarios, the first radio may be further configured toperiodically provide to the processor a current value of the eventcounter.

In some scenarios, the first radio may be further configured to provideto the processor an indication that the event counter has reached thefuture value.

In some scenarios, the first radio may be further configured to provideto the second radio an indication that the event counter has reached thefuture value. The second radio transitioning from the low-power state tothe high-power state may be in response to receiving the indication thatthe event counter has reached the future value.

In some scenarios, the value of the event counter matches a value in aremote event counter maintained by the remote wireless device.

A wireless communication device is disclosed, which may include a firstradio and a second radio. The first radio may be configured to receive,from a remote wireless device, an advertisement message according to afirst radio access technology (RAT); and to provide, to the secondradio, an indication that the advertisement message has been received,wherein the indication includes a timestamp indicating a time at whichthe advertisement message was received by the first radio. The secondradio may be configured to, in response to receiving the indication thatthe advertisement message has been received, transition from a low-powerstate to a high-power state at a set time, wherein the set time isdetermined by adding a first offset time to the time indicated by thetimestamp. While operating in the high-power state, the second radio mayreceive, according to a second RAT, acquisition information regarding asubsequent communication according to the second RAT, wherein thesubsequent communication follows the acquisition information by a secondoffset time, wherein the acquisition information indicates the secondoffset time. The second radio may be further configured to transitionfrom the high-power state to the low-power state after receiving theacquisition information.

In some scenarios, the second radio may be further configured totransition from the low-power state to the high-power state in responseto expiration of the second offset time. While operating in thehigh-power state, the second radio may receive the subsequentcommunication according to the second RAT. The second radio may beconfigured to transition from the high-power state to the low-powerstate after receiving the subsequent communication according to thesecond RAT.

In some scenarios, the advertisement message may indicate the value ofthe first offset time. In other scenarios, the offset time may bepredetermined.

In some scenarios, the indication that the advertisement message hasbeen received may include a medium access control (MAC) address to whichthe advertisement message was addressed. The second radio may be furtherconfigured to confirm that the acquisition information is also addressedto the MAC address.

In some scenarios, the first radio may include a first clock and thesecond radio may include a second clock. The second radio may be furtherconfigured to determine a value of the second clock upon detecting asignal edge on an interface between the first radio and the secondradio, and receive from the first radio a value of the first clock uponthe first radio detecting the signal edge on the interface between thefirst radio and the second radio. The second radio may be furtherconfigured to determine a difference between the value of the secondclock and the value of the first clock. Determining the time indicatedby the timestamp may include adjusting the value of the timestamp by thedifference between the value of the second clock and the value of thefirst clock.

Methods are presented for performing functions similar to thoseperformed by the wireless communication devices summarized above.

This summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtainedwhen the following detailed description of the embodiments is consideredin conjunction with the following drawings.

FIG. 1 illustrates an example wireless communication system, accordingto various exemplary embodiments described herein.

FIGS. 2-3 are block diagrams illustrating example wireless devices,according to various exemplary embodiments described herein.

FIG. 4 illustrates a signal flow diagram for synchronizing BT and UWBcommunications in a BT connection scenario, using a standardized BTradio, according to some embodiments.

FIG. 5 illustrates a signal flow diagram for synchronizing BT and UWBcommunications in a BT connection scenario, using an enhanced BT radio,according to some embodiments.

FIG. 6 illustrates a signal flow diagram for synchronizing BT and UWBcommunications in a BT non-connected scenario, according to someembodiments.

While the features described herein are susceptible to variousmodifications and alternative forms, specific embodiments thereof areshown by way of example in the drawings and are herein described indetail. It should be understood, however, that the drawings and detaileddescription thereto are not intended to be limiting to the particularform disclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the subject matter as defined by the appended claims.

DETAILED DESCRIPTION Incorporation by Reference

Various details of example UWB communication protocols are disclosed inIEEE 802.15.4-2015, which is hereby incorporated by reference as thoughdisclosed herein in its entirety.

Terminology

The following are definitions of terms used in this disclosure:

Memory Medium—Any of various types of non-transitory memory devices orstorage devices. The term “memory medium” is intended to include aninstallation medium, e.g., a CD-ROM, floppy disks, or tape device; acomputer system memory or random access memory such as DRAM, DDR RAM,SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash,magnetic media, e.g., a hard drive, or optical storage; registers, orother similar types of memory elements, etc. The memory medium mayinclude other types of non-transitory memory as well or combinationsthereof. In addition, the memory medium may be located in a firstcomputer system in which the programs are executed, or may be located ina second different computer system which connects to the first computersystem over a network, such as the Internet. In the latter instance, thesecond computer system may provide program instructions to the firstcomputer for execution. The term “memory medium” may include two or morememory mediums which may reside in different locations, e.g., indifferent computer systems that are connected over a network. The memorymedium may store program instructions (e.g., embodied as computerprograms) that may be executed by one or more processors.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which performs wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), portable gamingdevices (e.g., Nintendo DS™, PlayStation Portable™, Gameboy Advance™,iPhone™), laptops, wearable devices (e.g. smart watch, smart glasses),PDAs, portable Internet devices, music players, data storage devices, orother handheld devices, etc. In general, the term “UE” or “UE device”can be broadly defined to encompass any electronic, computing, and/ortelecommunications device (or combination of devices) which is easilytransported by a user and capable of wireless communication.

Wireless Device—any of various types of computer system devices whichperforms wireless communications. A wireless device can be portable (ormobile) or may be stationary or fixed at a certain location. A UE is anexample of a wireless device. Other examples may include less mobiledevices, such as desktop computers, entertainment centers, set-topboxes, climate control modules, security modules, smart home controlmodules, smart appliances, electronic doors/locks, vehicles, etc.

Communication Device—any of various types of computer systems or devicesthat perform communications, where the communications can be wired orwireless. A communication device can be portable (or mobile) or may bestationary or fixed at a certain location. A wireless device is anexample of a communication device. A UE is another example of acommunication device.

Base Station—The term “Base Station” (also called “eNB” or “gNB”) hasthe full breadth of its ordinary meaning, and at least includes awireless communication station installed at a fixed location and used tocommunicate as part of a wireless cellular communication system.

Link Budget Limited—includes the full breadth of its ordinary meaning,and at least includes a characteristic of a wireless device (e.g., a UE)which exhibits limited communication capabilities, or limited power,relative to a device that is not link budget limited, or relative todevices for which a radio access technology (RAT) standard has beendeveloped. A wireless device that is link budget limited may experiencerelatively limited reception and/or transmission capabilities, which maybe due to one or more factors such as device design, device size,battery size, antenna size or design, transmit power, receive power,current transmission medium conditions, and/or other factors. Suchdevices may be referred to herein as “link budget limited” (or “linkbudget constrained”) devices. A device may be inherently link budgetlimited due to its size, battery power, and/or transmit/receive power.For example, a smart watch that is communicating over LTE or LTE-A witha base station may be inherently link budget limited due to its reducedtransmit/receive power and/or reduced antenna. Wearable devices, such assmart watches, are generally link budget limited devices. Alternatively,a device may not be inherently link budget limited, e.g., may havesufficient size, battery power, and/or transmit/receive power for normalcommunications over LTE or LTE-A, but may be temporarily link budgetlimited due to current communication conditions, e.g., a smart phonebeing at the edge of a cell, etc. It is noted that the term “link budgetlimited” includes or encompasses power limitations, and thus a powerlimited device may be considered a link budget limited device.

Processing Element (or Processor)—refers to various elements orcombinations of elements. Processing elements include, for example,circuits such as an ASIC (Application Specific Integrated Circuit),portions or circuits of individual processor cores, entire processorcores, individual processors, programmable hardware devices such as afield programmable gate array (FPGA), and/or larger portions of systemsthat include multiple processors.

Wi-Fi—The term “Wi-Fi” has the full breadth of its ordinary meaning, andat least includes a wireless communication network or RAT that isserviced by wireless LAN (WLAN) access points and which providesconnectivity through these access points to the Internet. Most modernWi-Fi networks (or WLAN networks) are based on IEEE 802.11 standards andare marketed under the name “Wi-Fi”. A Wi-Fi (WLAN) network is differentfrom a cellular network.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

Configured to—Various components may be described as “configured to”perform a task or tasks. In such contexts, “configured to” is a broadrecitation generally meaning “having structure that” performs the taskor tasks during operation. As such, the component can be configured toperform the task even when the component is not currently performingthat task (e.g., a set of electrical conductors may be configured toelectrically connect a module to another module, even when the twomodules are not connected). In some contexts, “configured to” may be abroad recitation of structure generally meaning “having circuitry that”performs the task or tasks during operation. As such, the component canbe configured to perform the task even when the component is notcurrently on. In general, the circuitry that forms the structurecorresponding to “configured to” may include hardware circuits.

Various components may be described as performing a task or tasks, forconvenience in the description. Such descriptions should be interpretedas including the phrase “configured to.” Reciting a component that isconfigured to perform one or more tasks is expressly intended not toinvoke 35 U.S.C. § 112, paragraph six, interpretation for thatcomponent.

It is well understood that the use of personally identifiableinformation should follow privacy policies and practices that aregenerally recognized as meeting or exceeding industry or governmentalrequirements for maintaining the privacy of users. In particular,personally identifiable information data should be managed and handledso as to minimize risks of unintentional or unauthorized access or use,and the nature of authorized use should be clearly indicated to users.

FIG. 1—Wireless Communication System

FIG. 1 illustrates an exemplary (and simplified) wireless communicationsystem 100 in which aspects of this disclosure may be implemented. It isnoted that the system of FIG. 1 is merely one example of a possiblesystem, and embodiments of this disclosure may be implemented in any ofvarious systems, as desired.

As shown, the exemplary wireless communication system includes a(“first”) wireless device 102 in communication with another (“second”)wireless device 104. The first wireless device 102 and the secondwireless device 104 may communicate wirelessly using any of a variety ofwireless communication techniques, potentially including secure rangingwireless communication techniques.

As one possibility, the first wireless device 102 and the secondwireless device 104 may communicate using ultra wideband (UWB)communication technology (e.g., IEEE 802.15.4 WPAN communication), Wi-Fi(e.g., IEEE 802.11), and/or other techniques based on WPAN or WLANwireless communication. One or both of the wireless device 102 and thewireless device 104 may also be capable of communicating via one or moreadditional wireless communication protocols, such as any of Bluetooth(BT), Bluetooth Low Energy (BLE), near field communication (NFC), GSM,UMTS (WCDMA, TDSCDMA), LTE, LTE-Advanced (LTE-A), NR, 3GPP2 CDMA2000(e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), Wi-MAX, GPS, etc.

The wireless devices 102, 104 may be any of a variety of types ofwireless device. As one possibility, one or more of the wireless devices102, 104 may be a substantially portable wireless user equipment (UE)device, such as a smart phone, hand-held device, a wearable device, atablet, a motor vehicle, or virtually any type of mobile wirelessdevice. As another possibility, one or more of the wireless devices 102,104 may be a substantially stationary device, such as a set top box,media player (e.g., an audio or audiovisual device), gaming console,desktop computer, appliance, environmental controller, door, or any of avariety of other types of device.

Each of the wireless devices 102, 104 may include wireless communicationcircuitry configured to facilitate the performance of wirelesscommunication, which may include various digital and/or analog radiofrequency (RF) components, a processor that is configured to executeprogram instructions stored in memory, a programmable hardware elementsuch as a field-programmable gate array (FPGA), and/or any of variousother components. The wireless device 102 and/or the wireless device 104may perform any of the method embodiments described herein, or anyportion of any of the method embodiments described herein, using any orall of such components.

Each of the wireless devices 102, 104 may include one or more antennasfor communicating using one or more wireless communication protocols. Insome cases, one or more parts of a receive and/or transmit chain may beshared between multiple wireless communication standards. For example, adevice might be configured to communicate using either of Bluetooth orUWB using partially or entirely shared wireless communication circuitry(e.g., using a shared radio or at least shared radio components). Theshared communication circuitry may include a single antenna, or mayinclude multiple antennas (e.g., for MIMO) for performing wirelesscommunications. Alternatively, a device may include separate transmitand/or receive chains (e.g., including separate antennas and other radiocomponents) for each wireless communication protocol with which it isconfigured to communicate. As a further possibility, a device mayinclude one or more radios or radio components which are shared betweenmultiple wireless communication protocols, and one or more radios orradio components which are used exclusively by a single wirelesscommunication protocol. For example, a device might include a sharedradio for communicating using either of LTE or CDMA2000 1xRTT, andseparate radios for communicating using each of UWB, Wi-Fi, and/orBluetooth. Other configurations are also possible.

As previously noted, aspects of this disclosure may be implemented inconjunction with the wireless communication system of FIG. 1. Forexample, the wireless devices 102, 104 may communicate using one or moresynchronization techniques or features described subsequently hereinwith respect to FIGS. 4-6. By utilizing such techniques (and/or othertechniques described herein), the wireless device(s) may (at leastaccording to some embodiments) be able to achieve more efficientcommunication.

FIGS. 2-3—Exemplary Device Block Diagrams

FIG. 2 illustrates an exemplary wireless device 200 that may beconfigured for use in conjunction with various aspects of the presentdisclosure. For example, the device 200 may be an example of thewireless device 102 or the wireless device 104. The device 200 may beany of a variety of types of device and may be configured to perform anyof a variety of types of functionality. The device 200 may be asubstantially portable device or may be a substantially stationarydevice, potentially including any of a variety of types of device. Thedevice 200 may be configured to perform one or more synchronizationtechniques or features, such as any of the techniques or featuresillustrated and/or described subsequently herein with respect to any orall of FIGS. 4-6.

As shown, the device 200 may include a processing element 202. Theprocessing element may include or be coupled to one or more memoryelements. For example, the device 200 may include one or more memorymedia (e.g., memory 206), which may include any of a variety of types ofmemory and may serve any of a variety of functions. For example, memory206 could be RAM serving as a system memory for processing element 202.Other types and functions are also possible.

Additionally, the device 200 may include wireless communicationcircuitry 230. The wireless communication circuitry may include any of avariety of communication elements (e.g., antenna for wirelesscommunication, analog and/or digital communicationcircuitry/controllers, etc.) and may enable the device to wirelesslycommunicate using one or more wireless communication protocols.

Note that in some cases, the wireless communication circuitry 230 mayinclude its own processing element (e.g., a baseband processor), e.g.,in addition to the processing element 202. For example, the processingelement 202 might be (or include) an ‘application processor’ whoseprimary function may be to support application layer operations in thedevice 200, while the wireless communication circuitry 230 might includea ‘baseband processor’ whose primary function may be to support basebandlayer operations (e.g., to facilitate wireless communication between thedevice 200 and other devices) in the device 200. In other words, in somecases the device 200 may include multiple processing elements (e.g., maybe a multi-processor device). Other configurations (e.g., instead of orin addition to an application processor/baseband processorconfiguration) utilizing a multi-processor architecture are alsopossible.

The device 200 may additionally include any of a variety of othercomponents (not shown) for implementing device functionality, dependingon the intended functionality of the device 200, which may includefurther processing and/or memory elements (e.g., audio processingcircuitry), one or more power supply elements (which may rely on batterypower and/or an external power source) user interface elements (e.g.,display, speaker, microphone, camera, keyboard, mouse, touchscreen,etc.), and/or any of various other components.

The components of the device 200, such as processing element 202, memory206, and wireless communication circuitry 230, may be operativelycoupled via one or more interconnection interfaces, which may includeany of a variety of types of interface, possibly including a combinationof multiple types of interface. As one example, a USB high-speedinter-chip (HSIC) interface may be provided for inter-chipcommunications between processing elements. Alternatively (or inaddition), a universal asynchronous receiver transmitter (UART)interface, a serial peripheral interface (SPI), inter-integrated circuit(I2C), system management bus (SMBus), and/or any of a variety of othercommunication interfaces may be used for communications between variousdevice components. Other types of interfaces (e.g., intra-chipinterfaces for communication within processing element 202, peripheralinterfaces for communication with peripheral components within orexternal to device 200, etc.) may also be provided as part of device200.

FIG. 3 illustrates one possible block diagram of a wireless device 300,which may be one possible exemplary implementation of the device 200illustrated in FIG. 2. As shown, the wireless device 300 may include asystem on chip (SOC) 301, which may include portions for variouspurposes. For example, as shown, the SOC 301 may include processor(s)302 which may execute program instructions for the wireless device 300,and display circuitry 304 which may perform graphics processing andprovide display signals to the display 360. The SOC 301 may also includemotion sensing circuitry 370 which may detect motion of the wirelessdevice 300, for example using a gyroscope, accelerometer, and/or any ofvarious other motion sensing components. The processor(s) 302 may alsobe coupled to memory management unit (MMU) 340, which may be configuredto receive addresses from the processor(s) 302 and translate thoseaddresses to locations in memory (e.g., memory 306, read only memory(ROM) 350, flash memory 310). The MMU 340 may be configured to performmemory protection and page table translation or set up. In someembodiments, the MMU 340 may be included as a portion of theprocessor(s) 302.

As shown, the SOC 301 may be coupled to various other circuits of thewireless device 300. For example, the wireless device 300 may includevarious types of memory (e.g., including NAND flash 310), a connectorinterface 320 (e.g., for coupling to a computer system, dock, chargingstation, etc.), the display 360, and wireless communication circuitry330 (e.g., for UWB, LTE, LTE-A, CDMA2000, Bluetooth, Wi-Fi, NFC, GPS,etc.).

The wireless device 300 may include at least one antenna, and in someembodiments, multiple antennas 335 a and 335 b, for performing wirelesscommunication with base stations and/or other devices. For example, thewireless device 300 may use antennas 335 a and 335 b to perform thewireless communication. As noted above, the wireless device 300 may insome embodiments be configured to communicate wirelessly using aplurality of wireless communication standards or radio accesstechnologies (RATs).

The wireless communication circuitry 330 may include UWB Logic 332, aCellular Modem 334, and additional WLAN/PAN Logic 336. The UWB Logic 332is for enabling the wireless device 300 to perform UWB communicationsand/or for ranging communications, e.g., according to 802.15.4protocols. The WLAN/PAN Logic 336 is for enabling the wireless device300 to perform other WLAN and/or PAN communications, such as Wi-Fiand/or Bluetooth communications. The cellular modem 334 may be capableof performing cellular communication according to one or more cellularcommunication technologies.

As described herein, wireless device 300 may include hardware andsoftware components for implementing embodiments of this disclosure. Forexample, one or more components of the wireless communication circuitry330 (e.g., UWB Logic 332) of the wireless device 300 may be configuredto implement part or all of the methods described herein, e.g., by aprocessor executing program instructions stored on a memory medium(e.g., a non-transitory computer-readable memory medium), a processorconfigured as an FPGA (Field Programmable Gate Array), and/or usingdedicated hardware components, which may include an ASIC (ApplicationSpecific Integrated Circuit).

Assisted Timing Synchronization

Various RATs may have advantages and disadvantages relative to otherRATs, which may lead to each RAT being advantageous for particularapplications. For example, UWB communications, e.g., as described inIEEE 802.15.4-2015, incorporated by reference above, which is sometimesalso referred to as pulse radio, is capable of providing wirelesscommunications at low transmit power across large bandwidths (e.g., 500MHz or more), with precise timing. This technology is therefore wellsuited for short-range communications in which multi-path interferenceis a concern. For example, UWB communications are well suited for indoorranging and positioning applications, among other applications. However,an UWB radio may consume significant power while in a full-power state.Therefore, because UWB communications are often characterized by shortbursts between long periods of inactivity, causing an UWB radio toremain continually in a full-power state to listen for incomingcommunications is very wasteful of system power. Thus, initialsynchronization between UWB radios may, in some scenarios, be ahigh-cost operation, e.g., if one or more of the UWB radios must scanfor an initial discovery or synchronization message over an extendedperiod of time.

As another example, a BT radio may consume less power than an UWB radiowhile listening for incoming communications. Additionally, BTcommunications may have a longer range than UWB communications.Therefore, BT communications may be well suited to discovery ofsurrounding devices.

In light of the above, a first wireless device may use BT communicationsto perform discovery of and/or connection with a neighboring wirelessdevice. In the course of BT message exchange for discovery and/orconnection, the first wireless device may pass to the neighboringwireless device various information to synchronize subsequent UWBcommunications. For example, the first wireless device may use a BTcommunication to pass timing information regarding a time at which thefirst wireless device will transmit a subsequent UWB message.Additionally, the first wireless device and the neighboring wirelessdevice may use timing information of one or more BT communication eventsto synchronize the timing of their respective UWB radios forcommunicating the subsequent UWB message.

By synchronizing timing of the UWB radio of the first wireless devicewith the timing of the UWB radio of the neighboring wireless device, thepower efficiency of the UWB radios may be improved. For example, an UWBradio may operate in a low-power state, such as a sleep state, for amajority of the time. However, the UWB radio may enter a high-powerstate, such as a full-power state or a communication state, for one ormore brief window(s) of time to transmit and/or receive UWBcommunications, e.g., according to timing information passed via one ormore BT communications. Following such a window of time, the UWB radiomay return to the low-power state. Greater precision and accuracy insynchronizing the timing of the UWB radios may allow the UWB radios toutilize a narrower window of time to transmit and/or receive UWBcommunications, which may lead to increased power savings.

Performing the timing synchronization of the UWB radios may be performedaccording to any of various methods, e.g., as outlined below.

It should be understood that UWB communications and BT communicationsare merely examples, and that other RATs may be substituted. Forexample, any discussion of UWB communications throughout the followingmethods may be applied to any RAT that may benefit from precise wake-upperiods. Similarly, any discussion of BT communications throughout thefollowing methods may be applied to any RAT that may be capable ofcommunicating synchronization information for such wake-up periods.

FIG. 4—Synchronization in a BT Connected State

FIG. 4 illustrates a signal flow diagram for synchronizing BT and UWBcommunications in a BT connection scenario, using a standardized BTradio, according to some embodiments. As illustrated, the signal flowmay include a Tx device 400 and a Rx device 410. The Tx device 400 andthe Rx device 410 may each be, or include, or be included in, a wirelesscommunication device such as any of the wireless devices 102, 104, 200,or 300.

As illustrated, the Tx device 400 may include a Tx CPU 402, a Tx UWBradio 404, and a Tx BT radio 406, which may be communicatively coupledwith each other in various configurations. For example, the modulesshown within the Tx device 400 may be connected via one or more serialconnection(s), general purpose input/output (GPIO) connection(s), and/orother connection(s). The Tx CPU 402 may be, or include, or be includedin, an application processor, such as the processor(s) 302, and may beconfigured to run one or more applications or other software, e.g., toperform high-level communications processes for the Tx UWB radio 404and/or the Tx BT radio 406. The Tx UWB radio 404 may be, include, or beincluded in, the UWB logic 332, and may be configured to perform UWBcommunications, e.g., including the steps outlined below. The BT radio406 may be, include, or be included in the WLAN/PAN logic 336, and maybe configured to perform BT communications, e.g., including the stepsoutlined below.

As illustrated, the Rx device 410 may include a Rx CPU 412, a Rx UWBradio 414, and a Rx BT radio 416, which may be communicatively coupledwith each other in various configurations. For example, the Rx CPU 412,the Rx UWB radio 414, and the Rx BT radio 416 may be substantiallysimilar to the Tx CPU 402, the Tx UWB radio 404, and the Tx BT radio406, respectively.

As illustrated, the Tx BT 406 may transmit an advertisement (oradvertisement set) 420. In some scenarios, the Tx BT 406 may transmitsuch an advertisement periodically, e.g., at regular intervals, such as30 ms or 100 ms intervals. In some scenarios, the advertisement 420 maybe formatted or configured as defined by relevant BT standards.

In response to receiving the advertisement 420, the Rx BT radio 416 maytransmit a connection request 422. The connection request 422 may beconfigured to initiate a connection between the Rx BT radio 416 and theTx BT radio 406, and may include any information appropriate forinitiating such a connection. In some implementations, the connectionrequest 422 may be configured as defined by relevant BT standards. Upontransmitting the connection request 422, the Rx BT radio 416 may providea connection complete message 424 to the Rx CPU 412. The connectioncomplete message 424 may be provided substantially immediately followingtransmission of the connection request 422. Upon receiving theconnection complete message 424, the Rx CPU 412 may produce a timestampnoting the time, T_(RxC), at which the connection complete message 424was received. Specifically, the time T_(RxC) may be noted according tothe local clock of the Rx CPU 412.

In response to receiving the connection request 422, the Tx BT radio 406may provide a connection complete message 426 to the Tx CPU 402. Theconnection complete message 426 may be provided substantiallyimmediately following reception of the connection request 422. Uponreceiving the connection complete message 426, the Tx CPU 402 mayproduce a timestamp noting the time, T_(TxC), at which the connectioncomplete message 426 was received. Specifically, the time T_(TxC) may benoted according to the local clock of the Tx CPU 402.

Because the local clock of the Tx CPU 402 may not be synchronized withthe local clock of the Rx CPU 412, the times recorded as T_(RxC) andT_(TxC) may differ, even though the connection complete message 424 andthe connection complete message 426 may be received by the Rx CPU 412and the Tx CPU 402, respectively, substantially simultaneously. Thus,the times T_(RxC) and T_(TxC) may serve as a known reference time thatmay be used to coordinate subsequent communications.

It should be understood that additional signaling may occur followingthe connection complete message 424 and the connection complete message426, such as connection setup messaging, etc., which is not shown inFIG. 4, for simplicity.

The Tx CPU 402 may execute an application or other software that seeksto initiate a UWB communication, such as UWB ranging. The Tx CPU 402 maydetermine to transmit an UWB communication at a specific time. Followingreception of the connection complete message 426, the Tx CPU 402 mayfurther determine an offset time, T_(off), that indicates an amount oftime following T_(TxC) at which transmission of the UWB communicationwill begin. For example, T_(off) may indicate a value of 300 ms,indicating that the Tx UWB radio 404 will begin transmission of the UWBcommunication 300 ms after T_(TxC). In other words, the transmissiontime may occur at the time T_(TxC)+T_(off).

The Tx CPU 402 may communicate information regarding the impending UWBcommunication to the Rx CPU 412 via BT communications. For example, theTX CPU 402 may pass the information to the Tx BT radio 406, which maytransmit the information to the Rx BT radio 416 as a start UWB command428. The information passed to the Tx BT radio 406 and included in thestart UWB command 428 may include an indication that the Tx UWB radio404 will transmit an UWB communication, as well as the value of T_(off).In some scenarios, the information may also include other information,such as a type of communication to be sent.

As illustrated, the start UWB command 428 may not be successfullytransmitted on the first attempt. For example, the start UWB command 428a may represent a first attempt by the Tx BT radio 406 to transmit thestart UWB command 428, which may not be received successfully by the RxBT radio 416. For example, the Rx BT radio 416 may respond to the startUWB command 428 a with a NAK message (not shown) or may fail to respondwith an ACK message. In response, the Tx BT radio 406 may makesubsequent attempts, as necessary to complete the communication. In theexample scenario illustrated, the first two attempts, 428 a and 428 b,fail, but the Rx BT radio 416 successfully receives the start UWBcommand 428 c.

The Rx BT radio 416 may pass to the Rx CPU 412 the payload received inthe start UWB command 428, including the information regarding theimpending UWB communication, which may include, e.g., T_(off). Inresponse to receiving the information regarding the impending UWBcommunication, the Rx CPU 412 may prepare to receive the UWBcommunication via the Rx UWB radio 414. For example, the Rx CPU 412 maycommunicate to the Rx UWB radio 414 information or instructions 430 tocause the Rx UWB radio 414 to attempt to receive an UWB communication atthe time T_(RxC)+T_(off). In some implementations, the information orinstructions 430 may alternatively, or additionally, be communicated tothe Rx UWB radio 414 by the Rx BT radio 416.

In some implementations, the Tx UWB radio 404 and/or the Rx UWB radio414 may be configured to remain in a low-power state, such as a sleepstate, under normal conditions, but to enter an active state (e.g.,wake) to transmit and/or receive UWB communications at specific times.In such implementations, attempting to receive the UWB communication mayinclude the Rx UWB radio 514 temporarily entering the active state toreceive the UWB communication

As an example, the Tx CPU 402 may cause the Tx UWB radio 404 to wake ata certain time to transmit an UWB beacon 432. The time for thistransmission may be at the time T_(TxC)+T_(off). After transmitting theUWB beacon 432, the Tx UWB radio 404 may return to the low-power mode.

In response to receiving the information regarding the impending UWBcommunication, the Rx CPU 412 (or the Rx BT radio 416) may cause the RxUWB radio 414 to wake to receive the UWB beacon 432 at the timeT_(RxC)+T_(off). For example, the Rx CPU 412 may initiate a timerconfigured to expire at the time T_(RxC)+T_(off), and upon expiration ofthe timer, may provide to the Rx UWB radio 414 the instruction 430 towake immediately. As another example, the Tx CPU 412 may provide to theRx UWB radio 414 the instruction 430, including a time value indicatingthe time remaining until the time T_(RxC)+T_(off). The Rx UWB radio 414may then initiate a timer configured to expire at the timeT_(RxC)+T_(off), based on the time value provided by the Rx CPU 412, andthe Rx UWB radio 414 may wake upon expiration of the timer. In eitherexample, the Rx UWB radio 414 may wake for a time window that begins at(or is centered at, includes, etc.) the time T_(RxC)+T_(off). Becausethe time T_(RxC) is synchronized with the time T_(TxC), the Rx CPU 412and/or the Rx UWB radio 414 may know when the UWB beacon 432 will betransmitted, with a high degree of precision, so the wake window of theRX UWB radio 414 may be brief. The length of the wake window may bedetermined based on various factors, such as the expected length of theUWB beacon 432 and/or other communications, and the precision of thesynchronization, considering such factors as hardware delays, softwaredelays, clock precision, transmission times, etc. In some scenarios, thelength of the wake window may be a fixed, predetermined value. Followingthe wake window, the Rx UWB radio 414 may return to the low-power mode.

In some scenarios, subsequent communications may be performed withinsimilarly brief wake windows. For example, if the UWB beacon 432 is anUWB ranging request message, then the Rx UWB radio 414 may transmit anUWB ranging response message at a fixed, predetermined time followingreceipt of the UWB beacon 432, e.g., as known in the art. Thus, the RxUWB radio 414 and the Tx UWB radio 404 may each wake for a time windowappropriate to transmit/receive the UWB ranging response message.Alternatively, or additionally, the Rx UWB radio 414 and the Tx UWBradio 404 may be configured to wake periodically following a firsttransmission. Alternatively, or additionally, the UWB beacon 432 mayinclude information regarding one or more subsequent communications,including timing information, which may cause the Rx UWB radio 414and/or the Tx UWB radio 404 to wake at one or more subsequent times totransmit and/or receive the subsequent communications.

In some implementations, BT events other than connection completesignals may alternatively, or additionally, be used to synchronize thetiming of the Tx UWB radio 404 and the Rx UWB radio 414. For example, insome scenarios, the Tx BT radio 406 may transmit to the Rx BT radio 416a connection update message, e.g., to indicate a change in theperiodicity of BT advertisement messages. Upon transmitting such aconnection update message, the Tx BT radio 406 may provide to the Tx CPU402 a connection update event message. Upon receiving the connectionupdate event message, the Tx CPU 402 may produce a timestamp noting thetime, T_(TxU), at which the connection update event message wasreceived, e.g., according to the local clock of the Tx CPU 402.Similarly, upon receiving the connection update message, the Rx BT radio416 may provide to the Rx CPU 412 a connection update event message.Upon receiving the connection update event message, the Rx CPU 412 mayproduce a timestamp noting the time, T_(RxU), at which the connectionupdate event message was received, e.g., according to the local clock ofthe Rx CPU 412. Because the two connection update event messages may bereceived by the Rx CPU 412 and the Tx CPU 402 substantiallysimultaneously, the times T_(RxU) and T_(TxU) may serve as a knownreference time that may be used to coordinate subsequent communicationsin substantially the same manner as T_(RxC) and T_(TxC). This may allowthe synchronization of the UWB radios to be updated at a time afterconnection establishment, e.g., periodically.

In some implementations, yet other BT events may be similarly used tosynchronize, or update synchronization of, the Tx UWB radio 404 and theRx UWB radio 414.

FIG. 5—Enhanced Synchronization in a BT Connected State

FIG. 5 illustrates a signal flow diagram for synchronizing BT and UWBcommunications in a BT connection scenario, using an enhanced BT radio,according to some embodiments. As illustrated, the signal flow mayinclude a Tx device 500 and a Rx device 510. The Tx device 500 and theRx device 510 may each be, or include, or be included in, a wirelesscommunication device such as any of the wireless devices 102, 104, 200,or 300.

As illustrated, the Tx device 500 may include a Tx CPU 502, a Tx UWBradio 504, and a Tx BT radio 506, which may be communicatively coupledwith each other in various configurations. For example, the modulesshown within the Tx device 500 may be connected via one or more serialconnection(s), general purpose input/output (GPIO) connection(s), and/orother connection(s). The Tx CPU 502 may be, or include, or be includedin, an application processor, such as the processor(s) 302, and may beconfigured to run one or more applications or other software, e.g., toperform high-level communications processes for the Tx UWB radio 504and/or the Tx BT radio 506. The Tx UWB radio 504 may be, include, or beincluded in, the UWB logic 332, and may be configured to perform UWBcommunications, e.g., including the steps outlined below. The BT radio506 may be, include, or be included in the WLAN/PAN logic 336, and maybe configured to perform BT communications, e.g., including the stepsoutlined below.

As illustrated, the Rx device 510 may include a Rx CPU 512, a Rx UWBradio 514, and a Rx BT radio 516, which may be communicatively coupledwith each other in various configurations. For example, the Rx CPU 512,the Rx UWB radio 514, and the Rx BT radio 516 may be substantiallysimilar to the Tx CPU 502, the Tx UWB radio 504, and the Tx BT radio506, respectively.

In the scenario illustrated in FIG. 5, the Tx BT 506 has alreadyestablished a BT connection with the Rx BT radio 516. For example, theBT connection may be established in substantially the same manner asdescribed with regard to FIG. 4, e.g., by communicating theadvertisement (or advertisement set) 420, the connection request 422,the connection complete message 424, and the connection complete message426.

Following establishment of the connection, the Tx BT radio 506 mayperiodically perform a handshake function with the Rx BT radio 516. FIG.5 illustrates a plurality of handshake functions as dashed lines. Theperiodicity of the handshake function may be set, e.g., duringconnection establishment or at some other time, but may be known to boththe Tx BT radio 506 and the Rx BT radio 516. The Tx BT radio 506 and theRx BT radio 516 may each maintain a respective event counter (EC) thatis incremented each time the handshake function is performed. Thus, thevalue of EC and/or the time of the most recent handshake function mayserve as a known reference time value that may be used to coordinatesubsequent communications.

The Tx CPU 502 may execute an application or other software that seeksto initiate an UWB communication, such as UWB ranging. The Tx CPU 502may determine to transmit an UWB communication at a specific time. TheTx CPU 402 may receive from the Tx BT radio 506 a read EC message 526,including the current EC value, EC_(current). In the scenarioillustrated in FIG. 5, EC_(current) is 200.

In response to receiving the read EC message 526, the Tx CPU 502 maydetermine the EC value, EC_(UWB), representing what the EC value will beat the time the UWB communication will begin. For example, if the UWBcommunication will begin in 300 ms, and the handshake function isperformed with a period of 30 ms, then the EC value will increment 10more times before the UWB communication begins. Because EC_(current) wasreported by the read EC message 526 to be 200, the Tx CPU 502 maydetermine that EC_(UWB) will be 210. The Tx CPU 502 may communicateEC_(UWB) to the Rx CPU 512, e.g., via a BT communication. For example,the TX CPU 502 may pass EC_(UWB) to the Tx BT radio 506, which maytransmit the information to the Rx BT radio 516 as a start UWB command528. The start UWB command 528 may further include an indication thatthe Tx UWB radio 504 will transmit an UWB communication at EC_(UWB). Insome scenarios, the start UWB command 528 may also include otherinformation, such as a type of communication to be sent.

In some implementations, following (or concurrent with) transmission ofthe start UWB command 528, the Tx CPU 502 or the Tx UWB radio 504 maystart a timer to identify the time at which the UWB communication is tobe sent. In the present example, the timer may have a value of 300 ms,consistent with the timing information send in the start UWB command528. The Tx CPU 502 may cause the Tx UWB radio 504 to transmit the UWBcommunication upon expiration of the timer.

In other implementations, the Tx CPU 502 and/or the Tx UWB radio 504 mayuse any other method to determine the start time of the UWBcommunication. For example, after determining EC_(UWB), the Tx CPU 502may periodically obtain the current value of EC, and cause the Tx UWBradio 504 to transmit the UWB communication in response to determiningthat the EC value has reached EC_(UWB) (e.g., 210 in the example of FIG.5).

The Rx BT radio 516 may pass to the Rx CPU 512 the payload received inthe start UWB command 528, including the information regarding theimpending UWB communication, which may include EC_(UWB). The Rx BT radio516 may also provide to the Rx CPU 512 the value of EC_(current), basedon the event counter maintained by the Rx BT radio 516. For example, theRx BT radio 516 may provide to the Rx CPU 512 a read EC message 529,which may include EC_(current), e.g., as determined at or near the timethe Rx BT radio 516 receives the start UWB command 528 or the time theRx BT radio 516 provides the information regarding the impending UWBcommunication to the Rx CPU 512. A goal may be to strive to communicateto the Rx CPU 512 (e.g., via the read EC message 529) the same EC valuethat was communicated to the Tx CPU 502 via the read EC message 526.

In response to receiving EC_(UWB) and EC_(current), the Rx CPU 512 maystart a timer to identify the time at which the UWB communication is tobe sent (e.g., 300 ms in the example of FIG. 5). The Rx CPU 512 maycause the Rx UWB radio 514 to attempt to receive the UWB communicationupon expiration of the timer, e.g., by communicating to the Rx UWB radio514 information or instructions 530.

Alternatively, the Rx CPU 502, the Rx UWB radio 514 and/or the Rx BTradio 516 may use any other method to determine the start time of theUWB communication, based on the received value of EC_(UWB). For example,in some implementations, the Rx BT radio 516 may periodically provide tothe Rx CPU 512 the current value of EC, e.g., each time the value of ECis incremented, or at some less frequent interval. In response, the RxCPU 512 may cause the Rx UWB radio 514 to attempt to receive the UWBcommunication upon determining that EC has reached the value ofEC_(UWB). As another example, in some implementations, the Rx BT radio516 may determine the value of EC_(UWB) from the start UWB command 528.In response, the Rx BT radio 516 may provide an indication (e.g., raisea GPIO signal or report the current value of EC) to the Rx CPU 512and/or to the Rx UWB radio 514 upon incrementing the EC to the value ofEC_(UWB) (e.g., 210 in the example of FIG. 5). In response to theindication, the Rx UWB radio 514 may attempt to receive the UWBcommunication, or the Rx CPU 512 may cause the Rx UWB radio 514 toattempt to receive the UWB communication, e.g., by communicating to theRx UWB radio 514 information or instructions 530.

In some implementations, the Tx UWB radio 504 and/or the Rx UWB radio514 may be configured to remain in a low-power state, such as a sleepstate, under normal conditions, but to enter an active state (e.g.,wake) to transmit and/or receive UWB communications at specific times.In such implementations, attempting to receive the UWB communication mayinclude the Rx UWB radio 514 temporarily entering the active state toreceive the UWB communication.

As an example, the Tx CPU 502 may cause the Tx UWB radio 504 to wake ata certain time to transmit an UWB beacon 532. The time for thistransmission may be at the time that the value of EC is EC_(UWB) (e.g.,upon detecting that the EC has incremented to the value EC_(UWB)). Aftertransmitting the UWB beacon 532, the Tx UWB radio 504 may return to thelow-power mode.

As noted above, the Rx CPU 512 may cause the Rx UWB radio 514 to wake toreceive the UWB beacon 532 at the appropriate time. Because the BT eventcounter of the Rx BT radio 516 is synchronized with the BT event counterof the Tx BT radio 506, the Rx CPU 512 and/or the Rx UWB radio 514 mayknow when the UWB beacon 532 will be transmitted, with a high degree ofprecision, so the wake window of the RX UWB radio 514 may be brief.Following the wake window, the Rx UWB radio 514 may return to thelow-power mode.

In some scenarios, subsequent communications may be performed withinsimilarly brief wake windows, e.g., as outlined with regard to FIG. 4.

In various implementations, the BT radios 506 and 516 may communicate ECvalues to their respective CPUs 502 and 512 in any of various ways. Forexample, the BT radio may provide the current value of EC to therespective CPU via a serial or parallel connection, e.g., periodicallyor in response to a request from the CPU. As another example, the BTradio may have a dedicated output to provide the current EC value, whichmay be read by the CPU at any time. As another example, the Rx BT radio516 may include the current EC value when passing to the Rx CPU 512payload data from a BT communication, such as the start UWB command 528.

In some scenarios, the signal flow illustrated in FIG. 5 may allow moreprecise synchronization between the two UWB radios than the signal flowillustrated in FIG. 4. This may allow narrower wake windows for UWBcommunications, resulting in additional power savings. However, in someimplementations, custom BT hardware and/or firmware may be needed toenable output of the current EC value, which may lead to increasedhardware cost.

FIG. 6—Synchronization in a BT Non-Connected State

The scenarios illustrated in FIG. 4 and FIG. 5 allow for synchronizationbetween a Tx UWB radio and an Rx UWB radio based on knowledge of timingof BT events involved in establishing or maintaining a BT connection.However, in some scenarios, e.g., where the Tx device does not havepayload data to pass over BT, the Tx BT radio may not establish aconnection with the Rx BT radio. In such scenarios, it may still bepossible to use BT events to synchronize the Tx UWB radio and the Rx UWBradio.

FIG. 6 illustrates a signal flow diagram for synchronizing BT and UWBcommunications in a BT non-connected scenario, according to someembodiments. As illustrated, the signal flow may include a Tx device 600and a Rx device 610. The Tx device 600 and the Rx device 610 may eachbe, or include, or be included in, a wireless communication device suchas any of the wireless devices 102, 104, 200, or 300. In some scenarios,the Tx device 600 may be similar or identical to the Tx device 400 orthe Tx device 500, and the Rx device 610 may be similar or identical tothe Rx device 410 or the Rx device 510.

As illustrated, the Tx BT radio 606 may transmit an advertisement (oradvertisement set) 620. In some scenarios, the Tx BT 606 may transmitsuch an advertisement periodically, e.g., at regular intervals. Theadvertisement 620 may include a transmitter address and/or a receiveraddress (e.g. transmitter and/or receiver MAC addresses), authenticationinformation, and/or any other information appropriate for identifyingthe Tx device 600 and/or the Rx device 610 (e.g., identifying Tx BTradio 606 and/or the Rx BT radio 616).

In the scenario illustrated in FIG. 6, the Rx BT radio 616 may receivethe advertisement 620, but may decline to establish a connection withthe Tx BT radio 606.

However, the Rx BT 616 may provide to the Rx UWB radio 614 anadvertisement notification 624, e.g., via a serial interface or otherconnection. In some scenarios, the advertisement notification 624 mayinclude the advertisement 620, or some portion thereof, which mayinclude, e.g., the transmitter address and/or the receiver address, theauthentication information, etc. The advertisement notification 624 mayalso include a timestamp of the time, T_(RxA) at which the advertisement620 was received by the Rx BT radio 616. Alternatively, or additionally,the Rx BT 616 may provide the advertisement notification 624 to the RxCPU 612, which may then provide the advertisement notification 624, orsome portion thereof, to the Rx UWB 614.

In response to receiving the advertisement notification 624, the Rx UWBradio 614 may determine whether the advertisement was addressed to theRx device 610, e.g., using address information included in theadvertisement notification 624. If so, the Rx UWB radio 614 maytransition from a low-power state (e.g., a sleep state) to a high-powerstate (e.g., a full power state) capable of receiving UWBcommunications. Specifically, the Rx UWB radio 614 may perform thisstate transition upon expiration of an offset time, shown in FIG. 6 asUWB acquisition offset 628. For example, the Rx UWB radio 614 may starta timer to determine when the UWB acquisition offset 628 has elapsed,starting at the time indicated in the timestamp of the time at which theadvertisement 620 was received by the Rx BT radio 616. In other words,the Rx UWB radio 614 may initiate a timer configured to expire at a timedefined as (T_(RxA)+UWB acquisition offset 628). When the timer haselapsed, the Rx UWB radio 614 may transition to the high-power state fora predetermined window of time, to receive any available UWBcommunications, and may then transition back to the low-power statefollowing the window of time. In some scenarios, the UWB acquisitionoffset 628 may be predetermined. In some scenarios, the UWB acquisitionoffset 628 may be communicated in the advertisement 620, and passed inthe advertisement notification 624.

Upon transmitting the advertisement 620, the Tx BT radio 606 may provideto the Tx UWB radio 604 an advertisement notification 626. In somescenarios, the advertisement notification 626 may be similar to theadvertisement notification 624. For example, the advertisementnotification 626 may include the advertisement 620, or some portionthereof, which may include, e.g., the transmitter address and/or thereceiver address. The advertisement notification 626 may also include atimestamp of the time, T_(TxA), at which the advertisement 620 wastransmitted by the Tx BT radio 606.

The Tx CPU 602 may execute an application or other software that seeksto initiate a UWB communication, such as UWB ranging. The Tx CPU 602 maytherefore communicate to the Tx UWB radio 604 an instruction orinformation 630 to initiate UWB communications with the Rx device 610(e.g., with the Rx UWB radio 614). The connection instruction 630 isillustrated as occurring after the advertisement notification 626, butit may, in some scenarios, be communicated prior to the advertisementnotification 626 and/or the advertisement 620.

In response to receiving the advertisement notification 626, the Tx UWBradio 604 may start a timer to determine when the UWB acquisition offset628 has elapsed, starting at the time indicated in the timestamp of thetime at which the advertisement 620 was transmitted. In other words, theTx UWB radio 604 may initiate a timer configured to expire at a timedefined as (T_(TxA)+UWB acquisition offset 628). When the timer haselapsed, if the Tx UWB radio 604 has not yet received the connectioninstruction 630, then the Tx UWB radio 604 may take no further action atthat time, e.g., until receiving a subsequent advertisement notification626, reporting a subsequent advertisement 620 (e.g., if theadvertisements are transmitted periodically). Specifically, in suchscenarios, upon the timer elapsing, the Tx UWB radio 604 may remain in alow-power state, and not transmit any UWB communication. However, uponthe timer elapsing, if the Tx UWB radio 604 has received the connectioninstruction 630, as illustrated in FIG. 6, then the Tx UWB radio 604 maytransition from a low-power state to a high-power state capable oftransmitting UWB communications, and may transmit UWB acquisitioninformation 632. The Tx UWB radio 604 may then return to the low-powerstate.

The acquisition information 632 may include timing information, and anyother appropriate information, regarding subsequent UWB communications.For example, the subsequent UWB communications may be scheduled at oneor more time(s) independent of BT advertisements or other BT events. Asa specific example, the acquisition information 632 may include UWBcommunication offset 634, indicating an offset time at which the UWBbeacon 636 will be transmitted, relative to the time at which theacquisition information 632 is transmitted. In such an example, the TxUWB radio 604 may, upon transmitting the acquisition information 632,begin a timer having a duration matching the UWB communication offset634. Upon expiration of the timer, the Tx UWB radio 604 may transitionto the high-power state and transmit the UWB beacon 636. The Tx UWBradio 604 may then transition back to the low-power state.

In some implementations, the acquisition information 632 may beaddressed to the same receiver address (e.g., MAC address) as theadvertisement 620. In some implementations, the acquisition information632 may include the same transmitter address (e.g., MAC address) as theadvertisement 620. In some implementations, the Rx UWB radio 614 mayverify one or both of these addresses and/or other identificationinformation included in the acquisition information 632 to determinethat the acquisition information 632 is intended for the Rx UWB radio614, e.g., to avoid false synchronization with a third party.

As noted above, the Rx UWB radio 614 may transition to the high-powerstate for a window of time upon expiration of a timer measuring the UWBacquisition offset 628. If the Tx UWB radio 604 does not transmit theacquisition information 632, then the RX UWB radio 614 may receive nocommunication during this time window, and may transition back to thelow-power state, and take no further action until receiving a subsequentadvertisement notification 624. However, if the Tx UWB radio 604 doestransmit the acquisition information 632, then the Rx UWB radio 614 mayreceive the acquisition information 632 during the window of time duringwhich the Rx UWB radio 614 is in the high-power mode.

In response to receiving the acquisition information 632, the Rx UWBradio 614 may set a timer having a duration matching the UWBcommunication offset 634, as received in the acquisition information632. Upon expiration of the timer, the Rx UWB radio 614 may transitionto the high-power state and receive the UWB beacon 636. The Rx UWB radio614 may then return to the low-power state.

In some scenarios, subsequent communications may be performed withinsimilarly brief wake windows, e.g., substantially as outlined above withregard to FIG. 4.

In some implementations, the Rx BT radio 616 may operate according to adifferent (e.g., independent) clock than the Rx UWB radio 614. In suchimplementations, it may be beneficial to synchronize, or index, the twoclocks. For example, if the Rx BT radio 616 passes to the Rx UWB radio614, e.g., in the advertisement notification 624, a timestamp indicatingthe time at which the Rx BT radio 616 received the advertisement 620(wherein the timestamp would note the time according to the clock of theRx BT radio 616), then the Rx UWB radio 614 may be unable to identifythe corresponding time according to the clock of the Rx UWB radio 614,if the two radios were not synchronized or otherwise indexed.

In some implementations, synchronization of the clocks associated withthe Rx BT radio 616 and the Rx UWB radio 614 may be performed using aGPIO, or other low-latency connection. For example, the Rx BT radio 616and the Rx UWB radio 614 may each note the time according to itsrespective local clock upon a falling or rising edge of a signal passedon a GPIO between the two radios. One or both of the radios may thencommunicate the noted time to the other, and use the two times todetermine an offset between the two clocks.

In some implementations, synchronization of the clocks associated withthe Tx BT radio 606 and the Tx UWB radio 604 may be performed in asimilar manner.

In addition to the above-described exemplary embodiments, furtherembodiments of the present disclosure may be realized in any of variousforms. For example, some embodiments may be realized as acomputer-implemented method, a computer-readable memory medium, or acomputer system. Other embodiments may be realized using one or morecustom-designed hardware devices such as ASICs. Still other embodimentsmay be realized using one or more programmable hardware elements such asFPGAs.

In some embodiments, a non-transitory computer-readable memory mediummay be configured so that it stores program instructions and/or data,where the program instructions, if executed by a computer system, causethe computer system to perform a method, e.g., any of the methodembodiments described herein, or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets.

In some embodiments, a device (e.g., a wireless device 102 or 104) maybe configured to include a processor (or a set of processors) and amemory medium, where the memory medium stores program instructions,where the processor is configured to read and execute the programinstructions from the memory medium, where the program instructions areexecutable to implement any of the various method embodiments describedherein (or, any combination of the method embodiments described herein,or, any subset of any of the method embodiments described herein, or,any combination of such subsets). The device may be realized in any ofvarious forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. A wireless communication device, comprising: afirst radio configured to: establish a connection with a remote wirelessdevice according to a first radio access technology (RAT); provide anindication to a processor of the wireless communication device that theconnection has been established; after providing the indication,receive, from the remote wireless device, a notification that the remotewireless device will transmit a communication according to a second RAT,wherein the notification includes an offset time; and provide the offsettime to the processor; the processor, configured to: store a timestampindicating a time at which the processor receives the indication thatthe connection has been established; and provide to a second radio ofthe wireless communication device an instruction to receive thecommunication according to the second RAT at a set time, wherein the settime is determined by adding the offset time to the time indicated bythe timestamp; and the second radio, configured to: in response toreceiving the instruction to receive the communication according to thesecond RAT, transition from a low-power state to a high-power state atthe set time; receive the communication according to the second RAT; andtransition from the high-power state to the low-power state afterreceiving the communication according to the second RAT.
 2. The wirelesscommunication device of claim 1, wherein the first RAT is Bluetooth andthe second RAT is ultra wideband (UWB).
 3. The wireless communicationdevice of claim 1, wherein, in establishing the connection with theremote wireless device according to the first RAT, the first radio isconfigured to: receive, from the remote wireless device, anadvertisement message according to the first RAT; and transmit, to theremote wireless device, a connection request message according to thefirst RAT, in response to receiving the advertisement message.
 4. Thewireless communication device of claim 3, wherein, in providing theindication to the processor that the connection has been established,the first radio is configured to: provide an indication to the processorthat the connection request has been transmitted.
 5. The wirelesscommunication device of claim 1, wherein, in providing to the secondradio the instruction to receive the communication according to thesecond RAT at a set time, the processor is configured to: initiate atimer configured to expire at the set time; and in response toexpiration of the timer, provide to the second radio an instruction toimmediately receive the communication according to the second RAT. 6.The wireless communication device of claim 1, wherein, in transitioningfrom a low-power state to a high-power state at the set time, the secondradio is configured to: receive from the processor an indication of thetime remaining until the set time; in response to expiration of the timeremaining, transition from the low-power state to the high-power state.7. The wireless communication device of claim 1, wherein thecommunication according to the second RAT is an ultra wideband (UWB)ranging request message, wherein the second radio is further configuredto: transition from the low-power state to the high-power state at apredetermined time after receiving the UWB ranging request message; inresponse to receiving the UWB ranging request message, transmit an UWBranging response message while operating in the high-power state; andtransition from the high-power state to the low-power state aftertransmitting the UWB ranging response message.
 8. A wirelesscommunication device, comprising: a first radio configured to: maintainan event counter that is incremented in response to a periodic handshakeprocedure with a remote wireless device, according to a first radioaccess technology (RAT); receive, from the remote wireless device, anotification that the remote wireless device will transmit acommunication according to a second RAT, wherein the notificationindicates a future value of the event counter at which the communicationwill be transmitted; and a second radio configured to: transition from alow-power state to a high-power state when the event counter reaches thefuture value indicated in the notification that the remote wirelessdevice will transmit the communication according to the second RAT;receive the communication according to the second RAT; and transitionfrom the high-power state to the low-power state after receiving thecommunication according to the second RAT.
 9. The wireless communicationdevice of claim 8, wherein the first radio is further configured to:establish a connection with the remote wireless device according to thefirst RAT prior to receiving the notification that the remote wirelessdevice will transmit the communication according to the second RAT. 10.The wireless communication device of claim 8, further comprising aprocessor, wherein the first radio is further configured to: provide tothe processor the future value of the event counter; and provide to theprocessor a value of the event counter that is current at the time thefirst radio provides to the processor the future value of the eventcounter; wherein the processor is configured to: in response todetermining that the event counter has reached the future value, provideto the second radio an instruction to receive the communicationaccording to the second RAT; and wherein the second radio transitioningfrom the low-power state to the high-power state is in response toreceiving the instruction from the processor.
 11. The wirelesscommunication device of claim 10, wherein the first radio is furtherconfigured to: periodically provide to the processor a current value ofthe event counter.
 12. The wireless communication device of claim 10,wherein the first radio is further configured to: provide to theprocessor an indication that the event counter has reached the futurevalue.
 13. The wireless communication device of claim 8, wherein thefirst radio is further configured to: provide to the second radio anindication that the event counter has reached the future value; whereinthe second radio transitioning from the low-power state to thehigh-power state is in response to receiving the indication that theevent counter has reached the future value.
 14. The wirelesscommunication device of claim 8, wherein the value of the event countermatches a value in a remote event counter maintained by the remotewireless device.
 15. A wireless communication device, comprising: afirst radio configured to: receive, from a remote wireless device, anadvertisement message according to a first radio access technology(RAT); provide, to a second radio of the wireless communication device,an indication that the advertisement message has been received, whereinthe indication includes a timestamp indicating a time at which theadvertisement message was received by the first radio; and the secondradio, configured to: in response to receiving the indication that theadvertisement message has been received, transition from a low-powerstate to a high-power state at a set time, wherein the set time isdetermined by adding a first offset time to the time indicated by thetimestamp; while operating in the high-power state, receive, accordingto a second RAT, acquisition information regarding a subsequentcommunication according to the second RAT, wherein the subsequentcommunication follows the acquisition information by a second offsettime, wherein the acquisition information indicates the second offsettime; and transition from the high-power state to the low-power stateafter receiving the acquisition information.
 16. The wirelesscommunication device of claim 15, wherein the second radio is furtherconfigured to: transition from the low-power state to the high-powerstate in response to expiration of the second offset time; whileoperating in the high-power state, receive the subsequent communicationaccording to the second RAT; and transition from the high-power state tothe low-power state after receiving the subsequent communicationaccording to the second RAT.
 17. The wireless communication device ofclaim 15, wherein the advertisement message indicates the value of thefirst offset time.
 18. The wireless communication device of claim 15,wherein the offset time is predetermined.
 19. The wireless communicationdevice of claim 15, wherein the indication that the advertisementmessage has been received includes a medium access control (MAC) addressto which the advertisement message was addressed; and wherein the secondradio is further configured to confirm that the acquisition informationis also addressed to the MAC address.
 20. The wireless communicationdevice of claim 15, wherein the first radio comprises a first clock andthe second radio comprises a second clock, wherein the second radio isfurther configured to: determine a value of the second clock upondetecting a signal edge on an interface between the first radio and thesecond radio; receive from the first radio a value of the first clockupon the first radio detecting the signal edge on the interface betweenthe first radio and the second radio; determine a difference between thevalue of the second clock and the value of the first clock; whereindetermining the time indicated by the timestamp comprises adjusting thevalue of the timestamp by the difference between the value of the secondclock and the value of the first clock.